This invention relates to the use of high density metal oxide fillers in rubber compounds.
Rubber compounds have progressed from the use of untreated natural rubber to enormously complex polymeric systems, formulated with synthetic elastomeric polymers for such specific uses as vehicle tires, vibration dampers, and other products.
Early in the development of sophisticated rubber products, compounders of rubber products dispersed fillers into various polymers as a means of both providing physical reinforcement and bulk to the elastomeric polymer. Carbon black was the first material commonly used as a filler. Later, silica has become a preferred filler, both alone and in combination with carbon black. Use of silica fillers improves rubber properties such as reducing rolling resistance (measured using polymer physics properties such as hysteresis), increasing road traction (particularly on wet surfaces), and enhancing other properties vital to improved fuel economy for vehicles, whose tires are engineered with tread compounds including such fillers.
While silica-containing rubber compounds have become preferred for tread compounds, the search in the art continues for other materials that can improve these vital vehicle tire performance properties. Consumers, governments, and vehicle manufacturers demand ever-better vehicle tire performance. Tire manufacturers strain to reduce costs of meeting customer expectations.
What the art needs is another class of fillers for rubber compounding that can be used at least in vehicle tire tread compounding as a substitute for, or an enhancement to, conventional tire fillers, in order to further improve vehicle tire performance at potentially lower costs of manufacture.
Moreover, this need in the art generally exists for any rubber compound which may require specific viscoelastic performance properties that are currently unavailable in commercial rubber compounds. For example, nearly all rubber compounds can benefit from an extension of filler choices in unexpected directions, once the demonstration of specific viscoelastic performance properties is known to those specific rubber compounders for their own specific rubber products.
The present invention solves the problems in the art by providing another class of fillers which can improve rubber compounds ranging from vehicle tire components to rubber hoses to vibration dampers.
One aspect of the present invention is a method of using high density metal oxide fillers in rubber compounds, comprising the steps of (a) selecting a high density metal oxide filler according to its specific performance properties, and (b) introducing the filler into rubber polymers for subsequent mixing to create a vulcanizable rubber compound.
Another aspect of the present invention is a vulcanizable rubber compound, comprising at least one elastomer, including but not limited to natural or synthetic rubber, or blends thereof, and at least one high density metal oxide filler.
Another aspect of the present invention is a vehicle tire component made from the vulcanizable rubber compound identified in the paragraph above.
Another aspect of the present invention is a vehicle tire comprising at least the vehicle tire component identified above.
Another aspect of the present invention is a method of vulcanizing the rubber compound above, comprising the steps of mixing at least one elastomer, comprising a natural or synthetic rubber, and at least one high density metal oxide filler and polymerizing the rubber monomer.
A feature of the invention is the use of a high density metal oxide filler that replaces or augments conventional reinforcement fillers in rubber compounds in a manner that utilizes viscoelastic performance properties of the rubber compound for a specific end use.
An advantage of the invention is the ability of one skilled in the art to select a high density metal oxide filler according to its viscoelastic performance properties for a specific rubber compound for a specific use.
Another advantage of the invention is the possible reduction of cost of manufacture of the rubber compound by reducing the amount of expensive silica coupling agents which conventional silica-filled rubber compounds invariably contain by the reduction of silica required in the rubber compound. Preferably, this reduction aims toward elimination of silica as a reinforcing filler.
xe2x80x9cMetal oxide fillerxe2x80x9d means a chemical composition of a metal and an oxide, where the metal is selected from Groups IVA, VA, IB, VIB, VIIB and VIIIB metals, and reacted with oxygen.
xe2x80x9cHigh densityxe2x80x9d means a specific gravity of greater than about 5.7 g/cm3 and preferably greater than about 6.5 g/cm3 and most preferably greater than about 8 g/cm3.
Other features and advantages of invention will be disclosed in conjunction with an explanation of the embodiments of the invention in conjunction with the following drawings.